Microarray analysis of 1,25(OH) 2D 3 regulated gene expression in human primary osteoblasts

Though extensive studies have been conducted, questions regarding the molecular effectors and pathways underlying the regulatory role of 1,25(OH) ₂D ₃ in human osteoblasts other than cell differentiation and matrix protein production remain unanswered. This study aims to identify genes and pathways that are modulated by 1,25(OH) ₂D ₃ treatment in human osteoblasts. Primary osteoblast cultures obtained from human bone tissue samples were treated with 1,25(OH) ₂D ₃ (10 ^-7 M) for 24 h and their transcritptomes were profiled by microarray analysis using the Affymetrix GeneChip®. Statistical analysis was conducted to identify genes whose expression is significantly modulated following 1,25(OH) ₂D ₃ treatment. One hundred and fifty-eight genes were found to be differentially expressed. Of these, 136 were upregulated, indicating clear transcriptional activation by 1,25(OH) ₂D ₃. Biostatistical evaluation of microarray data by Ingenuity Pathways Analysis (IPA) revealed a relevant modulation of genes involved in vitamin D metabolism (CYP24), immune functions (CD14), neurotransmitter transporters (SLC1A1, SLC22A3), and coagulation [thrombomodulin (THBD), tissue plasminogen activator (PLAT), endothelial protein C receptor (PROCR), thrombin receptor (F2R)]. We identified a restricted number of highly regulated genes and confirmed their differential expression by real-time quantitative PCR (RT qPCR). The present genome-wide microarray analysis on 1,25(OH) ₂D ₃-treated human osteoblasts reveals an interplay of critical regulatory and metabolic pathways and supports the hypothesis that 1,25(OH) ₂D ₃ can modulate the coagulation process through osteoblasts, activates osteoclastogenesis through inflammation signaling, modulates the effects of monoamines by affecting their reuptake.